In industries where fluids are piped to other locations and especially when such fluids may be under high pressure and or contain caustic chemical entities, safety valves are employed. Safety Valves are generally components that are openable upon a command and closable automatically upon loss of the command. Action of this nature is commonly termed “failsafe” since the natural condition of the valve is closed and it will move to that position on its own if permitted to do so by a controller associated therewith.
Traditionally safety valves have used hydraulic actuation, which provides a great deal of force potential and a very easy way to maintain the force on a piston of the safety valve. One need simply lock the hydraulic line and the force remains. More recently however, environmental regulations regarding hydraulic oil and industry safety regulations requiring certain large amounts of hydraulic oil on hand have made the use of hydraulic actuators less favored.
Electrically actuated safety valves have become of more interest to many common industries including but not limited to the drilling and completion industry. Different types of electric motors including but not limited to linear motors, rotary motors, etc., have been the subject of increasing interest and have been shown capable of opening a safety valve and failing safe as the loss of power to the system. Due to power requirements for electrical actuators, many of these types of actuators while capable of holding a safety valve open, are not favored. Other devices that rely upon a mechanical interlock arrangement reduce power consumption but are inherently less “failsafe” as the various configurations have friction to overcome to disengage and allow closure of the safety valve. The art would well receive configurations and methods that allow electrically actuated safety valves to be held open without requiring a large power supply and without suffering the introduction of unquantifiable frictional forces in the failsafe mode of the safety valve.